Our present and planned investigations are concerned with the replication and maturation of hemopoietic cells in man, and the effects of deficiencies of vitamin B12 and/or folate on these processes. Our studies of the effects of alcohol on hemopoiesis will be continued and expanded in additional studies of various physiologic and pathologic states which may induce or aggravate megaloblastic anemia. Studies of thrombopoietin levels in plasma and development of an improved bioassay for thrombopoietin will be continued. Studies of adrenal function in patients with megaloblastic anemia will also be continued and expanded.